Chain slipping on middle cogs

[B19GRR]

Hi all,

I'm getting a bit annoyed by this now, trying to slog along at a steady cadence into a miserable headwind and then clunk my automatic gearbox decides to zip up or down a gear. I'm wondering if this is because I've got a 9sp rear mech (Campag Daytona) running on an 8sp cassetter/ergo system, is there a difference in the parallelogram geometry that might cause this, or is it just a cable tension problem? It only really seems to do it on the 3rd and 4th cog in the cassette, maybe the cassette is worn, it's rather old now and those are the gears I mostly slog along on, OK used to slog along on, now I'm too old and fat I only get to use them with a tail wind going downhill

My bike was originally a triple set up and I converted last year to a double as I'm now in the flatlands, and to be honest never really liked the triple even in the hills. I've still got the old triple rear mech so could go back to that and try to look nonchalant about having the dorky long cage hanging off the end!

Cheers,
Rob

[mowog]

Your 9spd mech will operate fine with 8spd Ergos and cassette. Re-check your indexing but if the chain feels like it is riding over the middle sprockets and not engaging then it's likely to be a worn chain and/or cassette - probably best to change both at the same time.

[B19GRR]

Thanks! Glad the rear mech is up to the job. I should have said I fitted a new chain late last year which could be said to be still in perfect condition due to lack of use. It's a KMC chain, rather than Campag, with one of those annoying quick open links, basically impossible to open by hand it seems. I'll whip the back wheel off and give the cassette a decent and see how it looks. Hopefully it'll be as simple as that.

Cheers,
Rob

[jesta1865]

hi, check the cassette as i got a similar thing once and until you were right close to it you could not see that the teeth were worn and causing it to slip.

hth

[Session]

If you recently fitted a new chain and haven't done many miles on it befoire it started skipping it is almost definitely a worn cassette and first thing to try.

[B19GRR]

Bum, as they say. I gave it all a good going over today on the stand and there was no getting away from the fact that the 9sp mech wasn't indexing correctly. I could adjust it so that it would just about work over a range of 3-4 gears but each shift was slightly too far to keep the chain in line. I've stuck the old 8sp mech on and it's indexing perfectly again, so I can only conclude that there is a difference in the geometry of the parallelogram, pita!

Gave the cassette a good clean, it's far from perfect but still serviceable I'd say. I'll have to wait until I can get out on it though to be sure. Hopefully later but as we've just had a thunderstorm and downpour it may have to wait.

Cheers,
Rob

[waughie]

I hate to say it but there is no such thing as a 9spd derailleur. Pretty much any mech will work on any speed cassette. For instance it is possible to set up a shimano xtr mech to do 5 speeds, and similarly a tourney can do 10 speed. indexing is all done through the shifters, not the mech.

I would hazard a guess that your cables are mucky, and needed cleaning or replacing, it is possible you bent the "9spd" mech, Or you have fitted the wrong cage length mech. They come in three sizes, short, medium and long.

[b2hbm]

B19GRR said:

Bum, as they say. I gave it all a good going over today on the stand and there was no getting away from the fact that the 9sp mech wasn't indexing correctly. I could adjust it so that it would just about work over a range of 3-4 gears but each shift was slightly too far to keep the chain in line. I've stuck the old 8sp mech on and it's indexing perfectly again, so I can only conclude that there is a difference in the geometry of the parallelogram, pita!

Gave the cassette a good clean, it's far from perfect but still serviceable I'd say. I'll have to wait until I can get out on it though to be sure. Hopefully later but as we've just had a thunderstorm and downpour it may have to wait.

Cheers,
Rob

There was a design change in the amount of cable pull per click on Campag shifters, which does make a difference to the rear mech performance. Memory is very hazy but I think it was that the older shifters pulled more cable per click than the current ones, anyway the result was that you couldn't mix old shifters with the new groupsets. IIRC this would be about the time of the 9sp groupsets because I'm still using a 9sp daytona set-up on one bike and I remember fussing about the shifters I bought at the time - 7-8yrs ago ?

Normally the rear mech is "dumb" and it's the shifter and it's cable pull which determines the indexing (assuming you're not trying to use a mixture of shimano/campag components) so you can normally ignore the 8-9-10sp label on the rear mech. If you've proved it is an indexing problem by reverting to the old mech, then it sounds like you're mixing these cross-over components ?

When I've had the worn cassette/new chain problem it's been that the chain jumps on a sprocket and slips, but it doesn't change to the next one, it stays in the same gear. It only happened under load, it would work fine just turning the pedals.

So if yours is changing a gear then I'd say it's the ergo/mech matching and short of replacing the ergos you might as well just use the old long cage mech until the drivetrain needs changing, then upgrade the lot.

[B19GRR]

Thanks Brian, that makes sense, the groupset fitted is of '96 vintage so predates 9sp by a fair old margin. I did get out on it in the evening and the gears behaved perfectly, zero slips or jumps. Only problem I noticed was on small-small gears the chain was rubbing against the inside of the large chain ring, but IIRC you're not supposed to run that gear combo on the old 8sp set ups anyway, think you can get away with it on the 10sp though with the thinner chain.

So all good in the end, one Daytona rear mech to shortly appear on fleabay.

Cheers,
Rob